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Netcraft: Web More Vulnerable Than Ever to Attack

Microsoft reissued the security bulletin for a chunked encoding vulnerability in its IIS Web server this week to upgrade the severity rating of the problem to "critical."

The decision to rerelease the bulletin comes after a similar vulnerability was discovered in the Apache Web Server and worms have been developed to exploit the flaws. Web server research and security outfit Netcraft declared that due to the problems in IIS and Apache, "the Web is more vulnerable to attack now than at any time previously."

Microsoft's version 2.0 of bulletin MS02-028 makes no changes to the original patch issued June 12. "Microsoft has increased the severity rating of this issue to 'critical.' The revision is in response to a significant change in the threat environment due to an increased focus on chunked encoding vulnerabilities in general, and the discovery of hostile code attempting to exploit similar vulnerabilities on other platforms," Microsoft's revised bulletin notes.

Netcraft, in the latest version of its monthly survey of Web server activity, estimates that a majority of Internet sites are likely to be accessible to the newly reported remote exploits.

"Although Netcraft cannot explicitly test for the vulnerability without prior permission from the sites, around half of the Microsoft-IIS sites on the internet have .htr mapping enabled, which indicates that the site is likely to be vulnerable to the attack, and indeed that some number will already be under the control of an external attacker," Netcraft wrote.

On the Apache side, Netcraft found that Apache administrators had upgraded more than 6 million sites to a non-vulnerable version of the open source Web server, but around 14 million Apache sites remain potentially vulnerable.

"With over half of the Internet's web servers potentially vulnerable, conditions are ripe for an epidemic of attacks against both Microsoft IIS and Apache-based sites, and the first worm, targeting sites running Apache on FreeBSD, has been spotted," Netcraft reported.

About the Author

Scott Bekker is editor in chief of Redmond Channel Partner magazine.